• Hepatocellular carcinoma (HCC) is the most common cancer of the canine liver.
• The majority of HCCs (~80 percent) are considered “massive” with a low rate of metastasis. The less common types of HCC, diffuse and nodular, have a much higher rate of metastasis with most cases spreading to other organs.
• Often, biopsies are needed to diagnose an HCC. This typically will involve surgical, laparoscopic, or image-guided procedures to take a sample of the mass. Occasionally, an HCC can be diagnosed by a fine needle aspirate, but this is usually less successful.

• Completely removing massive HCCs through surgery has the best prognosis for dogs, but for some patients, the cancer is too large to be safely removed.
• For dogs where surgery is not an option and conservative treatment is pursued, the median survival time is nine months.
• There is very limited research available on other methods for treating HCC in dogs.

• In human oncology, stereotactic radiation has become more common to treat both early stage and nonsurgical HCC. This typically involves between three and five high-dose radiation treatments delivered over the course of one week.
• The American Society for Radiation Oncology task force evaluating radiation therapy for HCC strongly recommends respiratory management during treatment. This involves monitoring the movement of the liver while the patient is breathing to make sure the radiation remains on target with the cancer.

• The initial aim of this clinical trial is to assess the overall safety and effectiveness of treating HCC in dogs with stereotactic radiation.
• The second aim of this clinical trial is to assess the overall safety and effectiveness of a stereotactic radiation protocol that eliminates the need for advanced monitoring of the liver’s motion.

Liver cancer is the third leading cause of cancer-related deaths worldwide, with developing countries being overrepresented. Results of this study may benefit human radiation locations that lack advanced respiratory monitoring and allow more people to be treated.

Dog owners can benefit from significantly decreased costs of treatment and follow-up testing.

• Confirmed diagnosis of hepatocellular carcinoma – either by biopsy or fine needle aspirate
• No previous radiation therapy of this tumor
• Complete blood count (performed within past six weeks)
• Blood chemistry panel (performed within past six weeks)
• Thoracic radiographs (or other thoracic imaging, performed within past six weeks)